import java.util.Scanner;

public class java20231126 {
    public static void main1(String[] args) {
        System.out.println("Hello world");
        System.out.println(100);
        System.out.println(3.14);
        System.out.println('A');
        System.out.println(true);
        System.out.println(false);
    }


    public static void main2(String[] args) {
        for (int i = 1; i < 10; i++) {
            for (int j = 1; j <= i; j++) {
                System.out.print(i + "*" + j + "=" + i * j + "  ");
            }
            System.out.println();
        }
    }


    public static void main3(String[] args) {
        for (int i = 1; i < 10; i++) {
            for (int j = 1; j <= i; j++) {
                System.out.printf("%d*%d=%2d ",j,i,i*j );
            }
            System.out.println();
        }
    }


    public static void main4(String[] args) {
        Scanner sc =new Scanner(System.in);
        int n = sc.nextInt();
        int x = 1;
        int sum = 0;
        for(int i = 1;i <= n;i++){
            sum += i*x;
            x *= -1;
        }
        System.out.println(sum);
    }


    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n =sc.nextInt();
        double sum= 0;
        for(int i = 1;i <= n;i++){
            double x = 1.0 / i;
            sum += x;
        }
        System.out.printf("%.6f",sum);
    }
}


